Production of Jets and Photons at ATLAS

M Stockton

doi:10.1016/j.nuclphysbps.2008.12.002

Abstract

The measurement of the production of jets and photons in ATLAS will provide ideal tests of perturbative QCD in a kinematic regime never observed before. Gaining a precise quantitative understanding of perturbative QCD is essential to searches for new physics at the LHC. In addition, differential cross-section measurements of jet and photon production can be used to constrain parton density functions. The detection of jets and photons in ATLAS is achieved by using finely segmented calorimeters, which surround an inner tracking system enclosed in a 2T solenoid field.

Highlights

Stockton slide 3 Jets are as close as we get to the individual quarks or gluons Parton level process is obscured by hadronisation, jet algorithms, etc. Inclusive di-jet events give a good probe into parton densities with a large cross section σ=4.5mb pTγ>25GeV (NLOJET++) Photons are a complementary probe of parton densities Free from uncertainties of jet reconstruction Direct photons σ=0.2μb pTγ>25GeV (JETPHOX) Di-photon qq,qg → γγ σ=21pb gg → γγ σ=8pb pTγ>25GeV (RESBOS 80
Weta1 = corrected width in 3 strips in the 1st samp

Summary

Introduction

Parton level process is obscured by hadronisation, jet algorithms, etc. Inclusive di-jet events give a good probe into parton densities with a large cross section σ=4.5mb pTγ>25GeV (NLOJET++). Parton level process is obscured by hadronisation, jet algorithms, etc. Inclusive di-jet events give a good probe into parton densities with a large cross section σ=4.5mb pTγ>25GeV (NLOJET++). Photons are a complementary probe of parton densities Free from uncertainties of jet reconstruction Direct photons σ=0.2μb pTγ>25GeV (JETPHOX)

Mark Simulated cross sections

Jets in ATLAS slide

PDF outcomes slide

Summary slide

Findings

Direct Photon LO diagrams